1. CRP Structure and Activity
C-reactive protein was first described by Tillett and Francis J. Exp. Med., 52:561-71 (1930)! who observed that sera from acutely ill patients precipitated with the C-polysaccharide of the cell wall of Streptococcus pneumonia. Other investigators subsequently identified the reactive serum factor as protein, hence the designation "C-reactive protein" or "CRP." Kilpatrick et al., Immunol. Res., 10:43-53 (1991), provides a recent review of CRP.
CRP is a pentameric molecule which consists of five identical subunits Osmand et al., Proc. Natl. Acad. Sciences. U.S.A., 74:739-743 (1977)!. This pentameric form of CRP is sometimes referred to as "native CRP."
The gene sequence for human CRP has been cloned Lei et al., J. Biol. Chem., 260:13377-13383 (1985)!. In addition, the primary sequences for rabbit CRP Wang et al., J. Biol. Chem., 257:13610-13615 (1982)! and murine CRP have been reported Whitehead et al., Biochem. J., 266:283-290 (1990)!, and is under investigation for rat, dog, horse, goat, and sheep. Clinical and laboratory observations have determined that the acute phase response, classically defined by the well-defined changes of the blood Pepys et al., Advances in Immunology, 34:141-212 (1983)!, develops during various states of disease and injury including malignant neoplasia, ischemic necrosis, and bacterial, viral, or fungal parasitic infections. Measurement of serum acute phase reactants such as CRP have been utilized in clinical tests for diagnosis and clinical management of patients with various conditions, including systemic lupus erythematosus (SLE) Bravo et al., J. Rheumatology, 8:291-294 (1981)!, rheumatoid arthritis Dixon et al., Scand. J. Rheumatology, 13:39-44 (1984)!, graft versus host disease Walker et al., J. Clin. Path., 37:1022-1026 (1984)!, as well as many other diseases.